Swing a green robot at a mobile games industry conference, and you'll hit a dozen developers grousing about Android. They'll say its users don't want to pay for games, and complain about the payment methods and game discovery features on Google's Android Market store.

With 550,000 new Android devices being activated every day, the platform's potential is huge, but paid games revenues have been distinctly below expectations. However, this week has seen three games firms buck the trend and talk about how well they're doing from making their games available on Google-powered smartphones.

First, there's Godzilab, which makes the excellent Stardunk and iBlast Moki games. Both have been ported to Android Market, and according to a blog post by the developer, Stardunk was downloaded more than one million times in its first two months on Android.

There are some good details in the post, such as the fact that Stardunk was generating around 16,000-17,000 downloads a day when hovering around 50th place in the free apps chart on Android Market, but that this rose to 50,000 a day when Google featured the app on the homepage, boosting it to 16th in the chart.

The real juice comes with Godzilab's comments on revenues, though. "For Stardunk which is a free app and thus monetize the usage and not the download, the average revenue per daily user is 3x lower compared to the iOS version," explains the company. "But this is compensated by being downloaded by more users on Android. As of today both versions have about the same revenue, and we covered our initial development cost really quickly."

The second company praising Android is Gameview Studios, a US developer acquired earlier in 2011 by Japanese mobile social games company DeNA. The studio says its Tap Fish game has been installed by five million Android users, which has resulted in two million monthly active players. More importantly, the average revenue per user (ARPU) is apparently approaching that of the iOS version.

"Many developers complain that Android only monetizes at a small fraction of their games on iOS, but that's not what we see," says co-founder Riz Virk in a statement. "Our Android games monetise almost on par with our iOS games, and as we focus on building out cool new features like live wallpaper, we expect usage, engagement and revenues on the Android platform to continue to climb."

Live wallpaper? Tap Fish has a new feature that's exclusive to Android: a live wallpaper that enables players to check their virtual fish tank from their homescreen, without actually starting the game. The point being that Gameview is clearly making enough money from Android to justify developing such exclusive features for the platform.

The third company publicly espousing its success on Android is not a developer, but rather a social games network: Papaya. The company says it has 25 million Android users who between them have bought 11 million in-app purchases of virtual items and currency.

Its average paying user spends $22.60 a month, and the more popular games on the Papaya network earn $20,000 a month on average. Papaya-enabled games like Treasure Fever and X-City generate monthly average revenue per paying user (ARPPU) of around $10.

Godzilab and Gameview are not getting into the nitty-gritty of exactly how much money they are making, it should be noted: they are comparing Android and iOS revenues without saying what those revenues are.

Even so, there is a clear trend: developers with games that are free to download and play, and which make their money from in-app payments and/or advertising, can make money from Android's growing scale as millions more devices are activated every week.

As ever, the caveat being that this only holds true for games that are good enough to persuade people to play often, and for a large enough proportion to part with cash for in-app content. The question now is what Google plans to do now to create a healthier market for paid games on Android to match its platform's freemium success.